Electric relay



B. E. GETCHELL ELECTRIC RELAY Filed Jan. 11, 1946 M .Bi'meia'? INVENTOR.

BENJAMIN E Gave/41.

ATTORNEY.

Patented Nov. 7, 1950 ELECTRIC RELAY Benjamin E. Getchell, Plainville, Conn., assignor to The Trumbull Electric Manufacturing Company, Plainville, Conn., a corporation of Connecticut Application January 11, 1946, Serial No. 640,483

8 Claims. 200 -122) My invention relates to thermostatically actuated protective devices of the character of United States Patents 1,681,851 and 2,116,098.

The main object is to provide a simplified structure which is reliable and which is capable of being reset manually or automatically as may be desired.

Such a relay is provided with a switch and a resistance ,heater which actuates or permits a switch to be actuated to open a circuit when the main circuit is overloaded. In the present case, the relay has a switch which controls a circuit through another device (not shown) related to or which in turn controls the main circuit which is to be protected or controlled.

Fig. 1 is a longitudinal sectional view of a relay embodying my invention, the switch being shown in the normal closed position. v

Fig. 2 is a transverse sectional view on the plane of the line 22 of Fig. 1. but showing the switch in the Off position.

Fig. 3 is a fragmentary view of the switch parts in open circuit position.

Fig. 4 is a similar view with the parts in automatic open circuit position.

Figs. 5 and 6 are detail views of parts of the switch.

Fig. 7 is a fragmentary detail showing a part of the resetting plunger and its relation to the supporting strip for the latch.

In the form shown, the device is designed to be mounted in fuse clips of any suitable form connected in the'circuit to be protected. The body consists of two parts of insulating material, the bottom part III and the main part having sides I land I! which form the housing for the heater and the switch. These are held together by the end caps l3 and I4.

A resistance heater strip I6 is mounted in the bottom part l0 and is connected at one end by a screw I! to the angle piece I! to which the cap I3 is secured by screw IS. The other end is bent over around the angle piece 23 and clamped against cap I! by screw 2|, the angle piece 23 being anchored by screw 22 to the base piece I 3. A bimetal arm 23 is thermally and mechanically connected at one end to the heater by the screw l1 and its opposite end is adapted to warp downwardly when heated.

The switch mechanism of the relay has terminals 25 and 23 which are connected with some remote control device (not shown). The spring switch armfl is secured at one end to the up-. per part or the housing by a bushing 23 in which the terminal screw 23 is seated. The other end 2 is biased downwardly against the insulating slide 29 which'rests on the movable tip 01' the bimetal arm 23. This slide is guided in grooves 30 in the side walls of the housing. On the uppfir face 0! the movable tip of the arm 21 is mounted a contact 3|. The other contact 32 of the switch is carried by the heel of a floating Z-shaped latch member 33 which is hinged in a slot 34 in the tip of a spring arm or support 35. The latter is mounted in the upper part of the housing and connected at one end to the terminal screw 26 and biased at its other end upwardly away from arm 11.

An adjustable calibrating screw 36 is mounted in the upper wall of the housing and serves as an abutment for the upper arm 31 of the latch member 33. The spring support 35 pushes the latch up against the calibrating screw thereby tending to rotate the latch in a clockwise manner about the tip of member 36. Movement of the calibrating screw moves the latch member 33 directly, and the spring support 35 indirectly, thus the calibrating screw serves not only to change the setting of the device but also acts as an abutment necessary in the operation of the device.

A plunger rod 33 projects downwardly from the button 39 which is guided in the top of the housing and pressed upwardly by spring 40, the shoulder 4| serving as a'limiting stop against the spring support 35.

The latch 33 is biased by the action of the spring support 35 toward the open circuit position of Fig. 3, where the latch foot 42 presses against the tip of the rod 33. By pressing the button and rod down, the latch can be swung from the open circuit position of Fig. 3 to the closed position of Fig. 1 where the contact 32 engages the tip of contact 3|.

In order to provide for automatic closin of the switch after an open circuit, 1 have flattened the sides 01 the plunger rod at 43 so that it slides freely through the narrow part 44 of the slot in the spring support 35. One end of slot 44 may beenlarged at 45 to facilitate assembly on the rod 33. By depressing the button and rotating it and the rod the shoulder H is brought beneath the edges of the slot 44 so that when the button is released the spring 4]! draws the plunger rod upwardly until the shoulder is stopped by the spring support 35 in the position of Fig. 4. With the plunger rod in this depressed tion, it will be seen that when the bimetal arm 23 and the switch arm 21 are depressed and the contact 3| disengases the latch contact 32, the latch can only move to the position of Fig. 4. If we now assume that the heater cools off due to the breakingof the control circuit, the bimetal arm 23 and the spring switch arm 21 will warp upwardly again so that the upper surface of contact 3| will engage the tip of contact 32 and again close the circuit through the relay switch.

The reset button simply pushes the latch back to reset position excepting when it is set for automatic resetting. When operated automatically, the switch arm and the latch member 33 separate or close according to the position of the thermostat.

An insulating strip 24 for instance of asbestos may be interposed between the heater and the switch if desired. If desired, the resilient switch arm 21 may be formed of thermostatic metal so as to attain some ambient temperature compensation. In such case, thermal insulation is required between the bimetal arm 23 and the arm 21.

at one end and having a switch contact at a movable end, a resilient supporting arm parallel to the switch arm, a latch member hinged to the supporting arm, a calibrating member serving as an abutment for a part of said latch member, a contact carried by the latch member and releasably coacting with the contact on the switch arm, means for retracting said switch arm from said latch contact, said means including a bimetal element actuated by an overload in the circuit, said latch member being biased by its supporting arm to move to an open circuit position when released by said switch arm, said latch member having an arm extending away from its contact and a resetting member coacting with said latch arm.

2. A relay including a spring switch arm having a switch contact, a, resilient supporting arm, a latch member hinged to the supporting arm, an abutment for a part of said latch member, a contact carried by the latch member and releasably coacting with the contact on the switch arm, said latch member having an arm extending away from its contact, a bimetal arm and a sliding insulator between the bimetal arm and the switch arm permitting lateral deflection and retraction of the switch arm, said latch member being biased by the resilient supporting arm to move to an open circuit position when the switch arm is retracted and a resetting member colatch contact, said means including a bimetal element actuated by an overload in the circuit, said latch member being biased by its supporting arm to move to an open circuit position when released by said switch arm, said latch member having an arm'atits other end extending away from its contact and a resetting member acting with said latter arm.

4. In a relay, a movable switch member having a contact, a resilient supportin arm, a bia -ed latch member hinged to said arm and having two oppositely extending arms a contact carried by said latch member and releasably coacting with the other contact to close a circuit through the movable switch member and the supporting arm, an abutment for one oi the arms of the latch member, said latch member being biased by the supporting arm toward an open circuit position, the switch member being movable to disconnect the contacts, means including a bimetal element actuated by an overload in the circuit of the relay for moving the switch member and disconnecting the contacts, a resetting member movable against the other arm of the latch member for relatching the contacts after they havebeen separated.

5. In a relay, a movable switch member having a contact, a spring supporting arm, a latch member hinged to said arm and having two arms, a contact carried by said latch member and releasably coacting with the other contact to close a circuit through the movable switch member and the supporting arm, an abutment for one of the arms of the latch member, said latch member being biased by the supporting arm towards an open circuit position, said switch member being movable to disconnect the contacts, means including a bimetal element actuated by an overload in the circuit of the relay f or moving the switch member and disconnecting the contacts, a resetting member movable toward the other arm of the latch member for relatching the contacts after they have been separated and means for setting the resetting member close to said latter arm in position to limit the movement of the latch and its contact.

6. In a relay, a movable thermostatically actuated switch member having a contact, a spring supporting arm, a latch member hinged to said arm and having two arms, a contact carried by said latch member and releasably coacting with the other contact to close a circuit through the movable switch member and the supporting arm, an abutment for one of the arms of the latch member, said latch member being biased by said supporting arm toward an open circuit position, said switch member being movable to disconnect the contacts, means including a bimetal element actuated by an overload in the circuit of the relay for moving the switch member and disconnectin the contacts, a resetting member movable against the other arm of the latch member for relatching the contacts after they have been separated and means for setting the resetting member close to said latter arm in position to limit the movement of the latch and its contact so that the movable switch contact can automatically reengage the latch contact.

'7. In a relay, a housing, a movable switch member mounted therein, a spring arm mountedin the housing and having a movable end, a latch member hinged to the movable end of said arm and having a contact adapted to releasably engage saidswitch memberfsaid latch member being biased by said sprin arm to move to an open circuit position, means, including a bimetal element for moving said switch member to disengage it from said latch contact upon an overload in the circuit through said latch member, said latch member having twoarms, an adjustable abutment for one of said arms and a spring pressed plunger coacting with the other arm for resetting the latch member.

8. In a relay, a housing, a movable switch member mounted therein, a spring arm mounted in the housing and having a movable end, a

5 latch member hinged to the movable end of said arm and having a contact adapted to releasably engage said switch member, said latch member being biased by said spring arm to move to an open circuit position, means, including a bimetal element for moving said switch member to disengage it from said latch contact upon an overload in the circuit through said latch member, said latch member having two arms, an adjustable abutment for one of said arms, a spring pressed plunger coacting with the other arm for resetting'the latch member and means for interlocking said plunger with said spring arm for holding the latch member in position for engagement b; said switch member.

BENJAMIN E. GETCI-IELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

